Bipolar transistor logic is ordinarily inplemented using well-known Schottky circuits to avoid transistor saturation, particularly where low power is to be employed. This class of circuit is typically in the form of transistor-transistor logic (TTL). A well-known product line is the FAST.RTM. integrated circuits. This is the Fairchild Advanced Schottky TTL logic family which is a registered trademark of National Semiconductor Corporation. Where higher power dissipation can be tolerated the wellknown emitter coupled logic (ECL) is commonly employed for high speed operation. These logic design families require special processing to create and must be specifically designed and fabricated.
By employing bipolar transistors in the current mode a number of advantages can be realized. First, the logic functions can be incorporated into area efficient designs. The current mode operation produces relatively high speed operation because the circuit nodes operate with greatly reduced voltage swings and the shunt capacitances do not have to be fully charged and discharged as is the case with voltage mode circuits. Finally, the circuits employ conventional bipolar transistors of the kind ordinarily employed in the well-known linear silicon, bipolar, junction-isolated, monolithic, integrated circuits. Thus, linear and digital circuits can easily be combined in low-cost, high-yield device structures.